More than 700 species of birds call Rwanda home. They have been able to exploit almost every conceivable niche or habitat across the country to find the food they need. To do so, birds have evolved many strategies to acquire their food, and with their high metabolism, high body temperature and the requirement to fly – birds need lots of energy and that means lots of food. ALSO READ: The birds that call Rwanda home Birds can be found looking for food on the ground, in water, in the canopy of trees and also up in the air. The Red-billed Firefinch and Red-cheeked Cordon-bleu are two such ground foraging birds commonly seen across Rwanda. Herons and hamerkops prefer to find their food in shallow water, whereas some kingfishers and cormorants dive for their dinner – a great place to see them doing so is along the edges of Lake Muhazi. ALSO READ: Rwanda’s birds – Finding a mate Whilst the Double-toothed Barbet and Ross’s Turaco can be found foraging for fruit in the canopy of Kigali’s trees, the various swallows and swifts all find their food in the air – these aerial hunters are best seen after heavy rain. Some species employ the help of other animals to find food. Cattle Egrets can be found in large numbers ‘hanging out’ with herds of livestock and other large herbivores, including elephants and hippos. These large animals attract flying insects which the egrets feed on. ALSO READ: Birds of Rwanda: Dressed to impress! The constant movement of the grazers also disturbs small prey items resting in the grass and on the ground, such as grasshoppers. Yellow-billed and Red-billed Oxpeckers are often seen perched on giraffes, buffalo and the various species of antelope in Akagera National Park. The oxpeckers feed on the parasites and insects found on these large grazers. This type of relationship, where both parties get something from it (food for one and the removal of parasites for the other) is called a symbiotic relationship. Most birds find their food by sight. However, research has shown that Hooded Vultures use sight, hearing and smell when trying to find food whilst on the wing. Researchers used sound recordings of lions and hyenas squabbling over a kill to show that vultures respond to sound cues whilst foraging for food. Previous research has also highlighted that vultures use smell to help locate food whilst soaring on the thermals above. I have had great experiences observing these critically endangered birds in northern Rwanda, most notably along the edges of Lake Ruhondo and Lake Kivu. Some birds have also developed resourceful ways to lure their prey to them – a great example of this can be seen here in Rwanda. Whilst standing in the shallow water of Akagera National Park’s Lake Ihema, Black Herons bring their wings around the front of their body to form what looks like an umbrella! The canopy prevents the sun from reflecting on the surface of the lake, which means the heron can get a better view of the fish in the water below. The shade of the ‘umbrella’ also attracts the fish towards it. With no hands and no teeth birds have developed ingenious ways to reach and handle their food. These adaptations enable them to exploit different habitats in the search for food. The primary adaptations involve the length and shape of a species bill/beak or tongue. The tropical climate here in Rwanda means that flowers are able to bloom all year round. To exploit this, the iridescently beautiful sunbird family have evolved curved beaks and long forked tongues so they can extract the sweet nectar from inside certain flowering plants. The Variable Sunbird, one of the smaller species can’t always reach into the deeper flowers so, instead it makes a small hole with its beak at the base of the flower and uses its long tongue to extract the nectar. These little iridescent gems can be found foraging in flowering plants across Rwanda. The woodpecker family is another great example of how adaptations have enabled birds to acquire a food source that would otherwise be unavailable to them. They have two toes pointing forward and two facing backwards which enables them to grip the bark of a tree from different angles. Their stiffened tail feathers are pushed against the tree to help support them as they away at the bark of the tree. (see accompanying photograph of an African Grey Woodpecker) Adaptations inside the skull allow woodpeckers to forcefully chisel away on the bark of a tree with their beak without injuring themselves. The tongue also has a barbed and sticky tip, and tiny muscles which means the tip can bend in any direction! This awesome extendable tongue - which extends to the back of their skull and around the top of it - is how woodpeckers are able to find and extract prey from deep inside a tree. Birds don’t have teeth which limits their ability to process food items. So, food is generally swallowed whole and then processed by their digestive systems. Birds that feed on live prey such as fish swallow them head first – by doing so, backward pointing spines and scales will not choke or injure the bird. Most birds have two stomachs. The first is called the crop, which is located on one or both sides of the oesophagus (throat) and is used to store food for later digestion or regurgitation to feed their young. The second, which all birds have is called the gizzard, this is where powerful muscles contract to crush the food and where nutrients are digested – doing the job teeth would have done. Some birds also swallow small stones and sand to help grind the food in the gizzard. To get rid of the indigestible parts of the food (scales, bones and gristle) many species will form them into pellets which are then regurgitated. Kingfishers, Bee-eaters and owls all do this. (see accompanying photograph of a Malachite Kingfisher) I am constantly amazed by the adaptations of the different birds – modifications that help them thrive in all sorts of different ways and in different environments!
